It is therefore reasonable to mitigate scattering in graphene-based systems for plasmonics (and devices for plasmonics in general) by suspending samples, or through the use of alternative substrates. [1]} In this work, for Ag films, the use of a hBN substrate (rather than the more traditional silicon) is found to shift plasmonic coupling towards surface modes, both diminishing bulk losses and enhancing the SPR peak amplitude. This effect is particularly dramatic in the case of the \(34\,\) nm Ag film (including those with no graphene top-coating), as an Ag film at this thickness on an SiO\(_2\) /Si substrate produces EELS that are extremely dominated by the bulk resonance. [2]} This is interesting in light of recent experimental results, showing electron mobility of graphene on hBN to be similar to that of suspended graphene. [3]} We expect SPR enhancement for other wide-bandgap substrates due to enhanced surface plasmon field confinement. Further comparison of alternate wide-bandgap substrate materials, such as SiC, are the subject of future work.
